Thorax 2000;55:547-549 ( July )

Inspiratory pressure support prolongs exercise induced lactataemia in severe COPD

Michael I Polkey^c, Peter Hawkins^a, Dimitris Kyroussis^c, Sheric G Ellum^a, Roy Sherwood^b, John Moxham^a

^a Department of Respiratory Medicine, King's College Hospital Campus, Guy's, King's and St Thomas' School of Medicine, London SE5 9PJ, UK, ^b Department of Clinical Biochemistry, ^c Respiratory Muscle Laboratory, Royal Brompton Hospital, London SW3 6HP, UK

Correspondence to: Dr M I Polkey email: m.polkey{at}rbh.nthames.nhs.uk

Received 16 September 1999; Returned to authors 7 January 2000; Revised version received 18 February 2000; Accepted for publication 30 March 2000

BACKGROUNDA physiological benefit from pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) is more probable if exercise is performed above the lactate threshold. This study was undertaken to investigate whether it was possible to extend the lactataemia of exercise using non-invasive inspiratory pressure support (IPS).
METHODSPlasma lactate levels were measured in eight men with severe COPD who performed two treadmill walks at an identical constant work rate to a condition of severe dyspnoea; the second walk was supported by IPS.
RESULTSMean plasma lactate levels before the free and IPS assisted walks were 1.65 mmol/l and 1.53 mmol/l, respectively (p = NS). Lactate levels increased during both walks to 2.96 mmol/l and 2.42 mmol/l, respectively (p = 0.01 for each) but the duration of the IPS assisted walk was significantly greater than the free walk (13.6 minutes versus 5.5 minutes, p = 0.01).
CONCLUSIONSPatients with severe COPD can sustain exercise induced lactataemia for longer if assisted with IPS. This technique may prove to be a useful adjunct in pulmonary rehabilitation.


Keywords: chronic obstructive pulmonary disease; exercise; lactataemia; inspiratory pressure support

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© 2000 by Thorax
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